Wt

The error popup is most likely caused by a WPanel (with several WPushButtons) hidden on creation and setHidden(false) later (after establishing a connection).
In addition, this panel suffers from WHBoxLayout::setSpacing() not having an effect until the page is reloaded in the browser.

related/similar to https://redmine.emweb.be/issues/12288

Trace output:

[2025-Sep-03 08:27:08.029] 1564436 - [access] "wthttp: 127.0.0.1   POST /?wtd=bwRJnL3A3nVKqYde HTTP/1.1 200 38036"
[2025-Sep-03 08:27:08.029] 1564436 - [info] "WebRequest: took 296309 ms"
[2025-Sep-03 08:27:08.146] 1564436 - [access] "wthttp: 127.0.0.1   GET /?wtd=bwRJnL3A3nVKqYde&sid=4162340155&webGL=true&scrW=2560&scrH=1387&tz=120&tzS=Europe%2FBerlin&htmlHistory=true&deployPath=%2F&request=script&rand=3731069149 HTTP/1.1 200 504495"
[2025-Sep-03 08:27:08.146] 1564436 - [info] "WebRequest: took 378.709 ms"
[2025-Sep-03 08:27:08.642] 1564436 - [access] "wthttp: 127.0.0.1   GET /resources/loading.png HTTP/1.1 200 4267"
[2025-Sep-03 08:27:08.939] 1564436 - [access] "wthttp: 127.0.0.1   POST /?wtd=bwRJnL3A3nVKqYde HTTP/1.1 200 479042"
[2025-Sep-03 08:27:08.939] 1564436 - [info] "WebRequest: took 114.26 ms"
[2025-Sep-03 08:27:09.602] 1564436 - [error] "WebController: could not parse request: Oversized application/x-www-form-urlencoded (17167323) at
0x7ffff799b851 (Wt::WException::WException(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)+0x41)
0x7ffff7885b67 (Wt::CgiParser::parse(Wt::WebRequest&, Wt::CgiParser::ReadOption) [clone .cold]+0x165)
0x7ffff7d7480b (Wt::WebController::handleRequest(Wt::WebRequest*)+0x13b)
0x7ffff7630275 (boost::asio::detail::executor_op<boost::asio::detail::binder0<std::_Bind<void (Wt::WebController::*(Wt::WebController*, http::server::HTTPRequest*))(Wt::WebRequest*)> >, std::allocator<void>, boost::asio::detail::scheduler_operation>::do_complete(void*, boost::asio::detail::scheduler_operation*, boost::system::error_code const&, unsigned long)+0xb5)
0x7ffff7a08065 (boost::asio::detail::scheduler::do_run_one(boost::asio::detail::conditionally_enabled_mutex::scoped_lock&, boost::asio::detail::scheduler_thread_info&, boost::system::error_code const&)+0x355)
0x7ffff7a01b81 (boost::asio::detail::scheduler::run(boost::system::error_code&) [clone .isra.0]+0x101)
0x7ffff7a01e35 (Wt::WIOService::run()+0x65)
0x7ffff6daadb4 (std::error_code::default_error_condition() const+0x34)
0x7ffff6a31aa4 (pthread_condattr_setpshared+0x684)
0x7ffff6abec3c (__clone+0x24c)
"
[2025-Sep-03 08:27:09.602] 1564436 - [access] "wthttp: 127.0.0.1   POST /?wtd=bwRJnL3A3nVKqYde HTTP/1.1 200 616"
[2025-Sep-03 08:27:09.602] 1564436 - [info] "WebRequest: took 108.699 ms"